Surgical procedures involving tissue or organs located in a patient's thoracic cavity (e.g., heart, lungs and the like) typically require a median sternotomy. That is, in order to gain access to tissue or organs located in a patient's thoracic cavity, it is oftentimes necessary for a midline sternal incision is made to allow the sternum to be separated laterally. After the surgical procedure is performed, the sternum must be reapproximated (i.e., closed). Conventionally, such reapproximation of the patient's sternum has involved using surgical stainless steel wires wrapped around (or through) the sternal halves so as to exert medial compression thereon. The wires are typically left in place permanently, unless a postoperative problem is encountered, in which case, a follow-up surgical procedure is performed to remove them. In this regard, a certain percentage of sternotomy patients experience chronic sternal pain postoperatively as a consequence of sternal nonunion due to inadequate sternal stability of the surgical wires.
Attempts have been made to offer substitutes for conventional surgical wiring techniques as evidenced by U.S. Pat. No. 4,201,215 to Crossett et al (hereinafter "Crossett et al '215), the entire contents of which are incorporated expressly hereinto by reference. According to the Crossett et al '215 patent, a sternum clamp is provided having a pair of elongate planar clamping members, each of which includes a clamping hook at one end thereof. One of the clamping members is provided with turned over, opposed lateral flanges defining guide groves which slidably receive a portion of the other clamping member. Thus, with the clamping hooks positioned in lateral engagement with a respective one of the patient's sternal halves, an end of the other clamping member may be brought into slidable engagement with the guide groove flanges. Thereafter, the guide groove flanges are crimped causing the device to bow slightly and thereby postionally lock the clamping members one to another.
Some potential problems may arise, however, using the sternal clamp disclosed in the Crossett et al '215 patent. For example, the positional restraint provided by the crimped guide groove flanges may not be sufficient in order to reliably laterally fix the clamp members one to another. That is, over time, it is entirely possible that the crimps could wear somewhat thereby reducing their frictional engagement with the clamp members. Furthermore, the crimps may not be sufficient to withstand the inherent lateral bias forces of the sternal halves over time. (Perhaps this is one reason why Crossett et al '215 additionally suggest the use of retaining wires threaded through holes formed in the sternal halves.) Any lateral shifting of the clamp members, and the resultant separation/movement of the patient's severed sternum could quite possibly create acute pain for the patient--a clearly undesirable effect.
On the other hand, the crimped guide groove flanges of the Crossett et al '215 device could possibly be difficult to uncrimp and/or otherwise loosen if separation of the clamping members were desired. Any such difficulties in separating the clamping members could therefore be quite problematic to an attending physician if a medical emergency arose during the procedure requiring relatively quick access to the organs and/or tissues of the patient's thoracic cavity, such as emergency sternal reopening after surgery for purposes of hemorrhage control and/or open heart massage.
In view of the problems identified above, improvements to sternal clamping devices generally are clearly needed. It is towards providing such improvements that the present invention is directed.
Broadly, the present invention is embodied in a separable sternal clamping device. Preferably, the sternal clamping device has a pair of opposed generally J-shaped clamp members which are laterally adjustable relatively to one another but can be rigidly joined, for example, via a set of machine screws. The machine screws most preferably are of a taper-headed variety which seat within a conformably shaped countersunk region of one of the clamp members so as to present a substantially flush upper surface. The machine screws are, however, of sufficient length so as to be coupled threadingly with a respective threaded aperture formed in the other clamp member. The clamp member and screws are most preferably formed of medical grade stainless steel.
The threaded coupling of the set screws with the other clamp member will thus rigidly unite the pair of clamp members one to another without lateral shifting occurring over time. Also, the clamp members may be rapidly disassembled and separated from one another (e.g., in case of a medical emergency requiring the surgeon to have access to the patient's thoracic cavity) by simply removing the set of screws therefrom.
These and other aspects and advantages of the present invention will become more clear after careful consideration is given to the following detailed description of the preferred exemplary embodiments thereof.